1. Technical Field
The present invention relates to an antenna-equipped film and a touch panel using the same.
2. Description of the Related Art
Touch panels are divided into a resistive film type, a capacitance type, an optical type, and the like. In recent years, the capacitance-type touch panels have been becoming mainstream. The capacitance-type touch panel is formed by combining transparent electrodes patterned vertically and horizontally. When a finger approaches the surface of the touch panel, the electrodes in the approached part change in capacitance and the capacitance change is detected to locate the approached position. The size of the touch panel varies from large sizes (for example, the diagonal dimension is 10 to 15 inches) to small sizes (for example, the diagonal dimension is 5 to 8 inches). The large-sized touch panel has a meshed electrode pattern using copper or silver as a low-resistance element to obtain the sensitivity equivalent to that of the small-sized touch panel.
The general touch panels are known to have a two-layer structure in which a sensor electrode pattern is formed on the front surface of a film base and a drive wiring pattern is formed on the back surface of the same. In addition, there are proposed various kinds of one-layer structures in which a sensor electrode pattern and a drive wiring pattern are formed on one surface of a film base for simplified manufacturing process and price reduction.
Further, touch panels containing an antenna separately from a touch sensor have been used in recent years (for example, refer to Japanese Utility Model No. 3160091). This kind of touch panel performs near field communication using the contained antenna with a communication partner such as an IC chip-incorporated card or a cellular phone. By containing an antenna pattern in a touch panel, it is possible to save space for a near field communication antenna or a Bluetooth® antenna that have been externally attached, thereby to provide a smaller-sized device.
Japanese Utility Model No. 3160091 discloses a touch panel with a near field communication antenna in which an antenna pattern constituting the antenna is formed on the touch panel. The antenna pattern inclines to form an angle of 15° or more relative to vertical pixel rows displayed on a display panel combined with the touch panel. According to this configuration, interference is unlikely to occur between the antenna pattern and the vertical pixel rows, thereby suppressing the appearance of moire.
In general, the start point and the terminal end of the antenna pattern are drawn out to the film end portions. To form a plurality of loop antenna patterns on one surface of the film base, the antenna patterns cross one another. Accordingly, it is necessary to form the antenna patterns on the both surfaces of the film base via through holes. This leads to increase in production price as compared to the formation on one surface.
When a touch panel electrode pattern is formed on the other surface of the film base, it is hard to form the antenna by antenna patterns on the both surfaces.
As an example of formation of an antenna pattern on one surface, Japanese Utility Model No. 3160091 discloses the touch panel equipped with a near field communication antenna. However, when the resonance point between the antenna pattern and the antenna of the communication partner does not match the desired value, it is necessary to re-form the antenna pattern for matching of the resonance point.